Method for stabilizing organic thionitrites



Patent d Sept. 7,,1943

UNITED m Es, PATENT OFFICE METHOD FOR ST ABILIZING ORGANI THIONITRITESGeorge S. Crandall, Woodbury, N. 3., Richard S. i "George, StateCollege, Pa, and Edwin M. Ny-

:gaard, Woodbury, N. 1., assignors to Socony- Vacuum Oil Com ny,Incorporated, New York N. Y., a corporation "of New York NoDrawing.Original application June 27, 1940,

Dividedand this applica tion December 2'1, 1941, Serial No. 424,597 H 18Claims. (01. 44 -53) Serial No. 342,692.

This application, which isa division of our copending application SerialNo; 342,692, filed June 27, 1940, relates to the stabilization of or-.

-. gines, which was attended by the further observation that theinstability of organic thionitrites made their practical value in thisregard questionable.

In preparing a fuel blend for compression ignition or Diesel engineswith an organic thionitrite, the thionitrite may be added to the fuel inthe pure state, it may be added to the fuel in solution in a suitablesolvent, or it may be formed in situ in the fuel or in another suitablesolvent, which in turn can be blended with the fuel. It is important,therefore, that the organic thionitrite be substantially stable againstdecomposition both prior to and after it's addition to the fuel, and thepresent invention is broadly directed to a method for effecting suchstabilization irrespective of the solvent in which it is dissolved.Typical solvents for the organic thionitrites are ether; carbondisulfide; carbon tetrachloride; and liquid hydrocarbons-such asbenzene, hexane, and petroleum fractions such as gasoline, kerosene,fuel oils, and heavier fractions such as lubricating oils.

The organic thionitrites are compounds having the general formula RSNO.They may be synthesiz ed inyarious ways as by the-reaction of a sludgeorsludgy materials and loss of the enhanced ignition quality.

Our invention is predicated upon the discovery that 'a Diesel fueloil-organic thionitrite blend can be stabilized by admixing therewithaminor proportion of a compound which will prevent the accumulation ofthe higher oxides of nitrogen in the blend. This may be explained on thetheory that the higher oxides of nitrogen apparently accelerate, bycatalytic action and by direct reaction, the decomposition of thethionitrite and are instrumental in the formation of sludge and sludgymaterials from constituents naturally occurring in the fuel oil. i

The compounds which will. prevent the accumulation of oxides of nitrogenin the blend may be roughly divided into two classes, depending upon themanner in which their purpose is accomplished. Thus, the accumulation ofthe higher oxides of nitrogen may lie prevented by adding to the blend acompound which will absorb or react with such oxides as they are formedto form stable, harmless products. hereinafter appear, this may beaccomplished by the addition of a compound which has antioxidantproperties: that is, a compound which will act as a negative catalysttoward the oxidation of organic thionitrites or nitric oxide or both.-

mercaptanwith nitrosyl chloride, or. preferably bytheninterreactionof amercaptan with anal kali nitrite and a mineral acid in a"non-homogeneous liquid system as described in ourcopending applicationSerial No.' 338,736, fi1ed June 4, 1940.,

Although, as" aforesaid, this invention is broad ly directed to thestabilization of organic thionitrites in solution irrespective of thesolvent, the principal object of' the present invention is to provide almethod for stabilizing organicthionitrites in Diesel fuel on blendscontaining them.

Theinstability of organic thionitrites in' Diesel fuel oil solutionsmanifestsitself by the lossof the typical thionitrlte color, developmentof In further explanation of the foregoing it has been shown (Ber. 59,1314 (1926)) that organic The nitric oxide formed in the formerdecomposition is oxidized to, the higher oxides, which,

as stated above, apparently actcatalytically to accelerate thedecomposition of the thionitrite and react with naturally-occurringconstituents.

in the oil, such as unsaturated hydrocarbons, etc,

to form sludgy materials. The higher oxides of Also, as will nitrogen(mo. and moo also react with many of the thionitrites to set up chainreactions which ultimately lead to sulfonic acids, sulfonee, etc., andoxide of nitrogen.

Thus, it will be seen that the various deterioration phenomena may beretarded by adding to the blend a compound which will actually removethe higher oxides of nitrogen as they are formed or which will act as anantioxidant to prevent their formation. We have discovered a generalclass of compounds which may be readily dissolved in an organicthionitrite solution such as,

a Diesel fuel oil-thionitrite blend to accomplish the purpose of thisinvention. Some, of these compounds'apparently act by absorbing orreacting with the oxides of nitrogen, and others act or sulphur atom;and n is at least one, effectively prevent the accumulation of oxides ofnitrogen in an organic thionitrite solution such as the aforesaid Dieselfuel-thionitrite blend. Typical compounds falling into this group are thaliphatic alcohols such as amyl alcohol (fusel oil), isopro- Dylalcohol, ethylene glycol, dodecyl alcohol, etc.;

the aliphatic mercaptans such as amyl mercap-.

tans, mixed aliphatic mercaptans (from mineral oil) tertiary butylmercaptan, etc. In this group preference is given to the, aliphaticmercaptans, with particular preference to tertiary butyl mercaptan.

The compounds contemplated herein may be classified according to theaforesaid theory of their stabilizing action as follows: the action ofthe aliphatic alcohols is apparently to remove oxides of nitrogen fromthe blend; and the action of the aliphatic mercaptans is twofold in thatthey apparently act as antioxidants and also to remove "oxides ofnitrogen from the blend.

' To demonstrate the eflicacy of the compounds contemplated herein asstabilizers for'Diesel fuel oil-thionitrite blends, we prepared a Dieselfuel oil blend containing 1% of amyl thionitrite, and representativestabilizers were added to samples of the blend, which were then storedin two sets under difierent conditions. One set wa stored "dryin' glassbottles; the other was stored in glass bottles containing water and aniron nail. The effectiveness ofthe stabilizer was determined primarilyby the length of time during which the red color of the thionitritepersisted and the length-of time before there was an appearance ofsludge in the oil. Table I below gives th results obtained with thesamples stored "dry," and Table 11 sets forth the results obtained withthe Titian Samples stored over water in presence of iron 1 1 2. 5 e 8 242. 5 v a s 2. 5 a 8 8 2. 5 24 24 p 2. 6 24 24 Tertiary butyl mercaptan2. 5 10 17+ addition foregoing stability tests we have made comparativecetane number determinations on Diesel fuel oil-thionitrite blendscontaining a representative stabilizing agent (amyl alcohol or fusel'oil). In these tests, the results of which are tabulated in Tables IIIand IV below, we have employed diflerent organic thionitrites invariousconcentrations as indicated.

. The fuel oil used for the tests tabulated in Table III was a straightrun Diesel oil having an A. P. I. gravity of 40.1 and a cetane number(C. N.) of 52 in the unblended state. The fuel oil used for obtainingthe results of Table IV was a catalyticallycracked Diesel fuel oilhaving an A. P.I. gravity of 26.8 and a cetane number of 27. The cetanenumber determinations were made according to the method described inTABLE III Th P I ioer or Ing nitrite ce t b gzgg g cent by O. N. creaseP added weight weight in .N

.1(a) Amyl. 1.0 None... 54.0 2. 0 150%-- do 1.0 AmylaleohoL. 2.5 65.513.5 2 a do 0. 5 None 58.0 6. 0 2(bg do 0. 5 Amyl alcohoL. 1. 25 65. 513. 5 35a t-Butyl 0. 25 None 59.0 7.0 3 b) do 0.25 AmylalcohoL. 0.6203.0 11.0 4 None. do 5.0 52.0 0. 0

TABLE IV 1m t-Butyl- 2. 0 No 30.00 a. 00 1 b do 2.0 AmylalcohoL. 5.036.0 9.0 2 a Ethyl. 2.0 None 31.0 4. 0 2 0).. do. 2.0 AmylalcohoL 5.036.5 9.5 3"... None do .0 27.0 0.0

samples stored over 5% by volume of water with i an iron nail in eachsample. Both sets of samples were stored at prevailing room temperature.

- v months) storage period.

In addition to the foregoing data, we have made determinations to showthe effectiveness of representative stabilizers over a prolonged (sixThe fuel used in these tests wa the catalytically cracked Diesel fueloil stock described above in connection with Table IV. The thionitritewas a mixed alkyl thionitrite prepared from a mixture of crudemercaptans obtained from mineral oil. It will be observed from theresults in Table V below .thatthe blankthat is, the fuel oil with 1% ofthe thionitritkf dropped in cetane number from' 33-to 29 in the sixmonths period, losing ,4 points in cetane number, while the samplesstabilized by thead- TABLE V Per cent Per cent 0. N.

by weight Stabilizer" by original after Change thinoitrite weight 0 mos.

1 None -33 29 -4 6 Fuscl 011.. 34 37 +3 2 d0 2 33 32 1 It will beobserved from the foregoing results that an organic thionitrite solutionsuch as a Diesel fuel oil blend containing an organic thionitrite may bestabilized against deterioration by the addition thereto of compoundsdescribed hereinabove which will prevent the accumulation of oxides ofnitrogen in the blend. The eifec-' tiveness of the various compounds,characterized by the foregoing general formula, in such an oil blend maybe explained either on the theory that they react with or absorb oxidesof nitrogen as they are formed, or on the theory that they act asantioxidants to prevent their formation, or both. The stabilizers may beadded in varying proportions, depending upon the manner in which theyact, the character and amount of thionitrite in the blend, etc., and ingeneral they produce the desired stabilizing effect in amounts rangingfrom about 0.01 to about 5 times the quantity of thionitrite present inthe solution.

We claim:

1. The method of stabilizing an organic thionitrite-solution againstdeterioration which comprises admixing with said solution aminorproportion of a compound having the general formula R(XH) in which Rrepresents an alkyl' radical, X is selected from the group consisting lof oxygen and sulphur, and n represents a whole number equal to at leastone. r i

2. The method of stabilizing an organic thionitrite solution againstdeterioration which comprises admixing with said solution a minorproportion of an aliphatic mercaptan. 3. The method of stabilizing anorganic thionitrite solution against deterioration which comprisesadmixing with said solution a minor proportion of tertiary butylmercaptan.

4. The method of stabilizing an organic thionitrite solution againstdeterioration which comprises admixing with said solution a minorproportion of my! mercaptan.

5. The method of stabilizing an organic thionitrite solution againstdeterioration which comprises admixingwith said solution a minorproportion'of an aliphatic alcohol.

i '3 l 6. The method of stabilizing an organic thionitrite solutionagainst deterioration which comminor proportion of a compound having thegen-- eral formula R(XH) in which R represents an alkyl radical, -X isselected from thegroup consisting of oxygen and sulphur, and n is awhole number equal to at least one.

8. The method of stabilizing a blend of Dieselfuel and an organicthionitrite against deterioration which comprises admixing with saidblend a minor proportion of an aliphatic alcohol.

9. The method of stabilizing a blend of Diesel fuel and an organicthionitrite against deterioration which comprises admixing with saidblend a minor proportion of fusel oil.

10. The method of stabilizing a blend of Diesel fuel and an. organicthionitrite against deterioration which comprises admixing with saidblend a minor proportion of an aliphatic mercaptan.

11. The method of stabilizing a blend of Diesel fuel and an organicthionitrite against deterioration which comprises admixing with saidblend a minor proportion of tertiary butyl mercaptan. 12. The method ofstabilizing a blend of Diesel fuel and an organic thionitrite againstdeterioration which comprises admixing with said blend a minorproportion of amyl mercaptan.

13. A Diesel fuel having in admixture therewith an organicthionitriteand a compound having the general formula R(XH) n in which Rrepresents an alkyl radical, X is selected from the group consisting ofoxygen and sulphur, and n is a whole number equal to at leastone.

14. A Diesel fuel having in admixture therewith an organic thionitriteand an aliphatic alcohol.

15. A Diesel fuel having in admixture therewith an organic thionitriteand fusel oil.

16. A Diesel fuel having in admixture therewith an organic thionitriteand an aliphatic mercaptan.

17. A Diesel fuel having in admixture therewith an organic thionitriteand tertiary butyl mercaptan.

18. A Diesel fuel having in admixture there? with an organic thionitriteand amyl mercaptan.

GEORGE S. CRANDAIL. RICHARD S. GEORGE. EDWIN M. NYGAARD.

